The field of this invention relates to a new and improved construction of a flexible electromagnetic pulse shielding conduit for electrical conductors.
In the past, it has been common to encase electrical conductors that extend from one location to another. The conducting of electrical conductors is required for operating electrical "equipment" remote from the source of the electrical generating signal apparatus. A typical location of where a substantial number of electrical conductors are utilized to operate remote equipment would be within an aircraft or other vehicles.
In the past, it has been common to principally shield the electrical conductors from moisture. When dealing with military equipment and particularly when dealing with the electrical conductors that operate critical equipment, it also has been necessary to protect the conductors from exterior electrical disturbances. Common forms of exterior electrical disturbances are electromagnetic interference and radio frequency interference. It has been common in the past to construct shielding conduits to protect electrical conductors from such types of interference.
However, there is another type of interference to which electrical conductors are susceptible, and that is termed "electromagnetic pulse". An electromagnetic pulse comes from sources such as a nuclear detonation. It has been found that even the detonation of a relatively small sized nuclear weapon that is strategically placed within the atmosphere can cause an extensive amount of damage to electronic equipment. This damage manifests itself in two effects. The first effect is hardware damage, usually in the form of semiconductor burnout. The second effect is electronic upset, ususally in the form of data transmission loss, or loss of stored data.
An electrical conductor may be shielded against electromagnetic and radio frequency interference, but not be shielded against electromagnetic pulse. This pulse, when picked up by the electrical conductors, is conducted into the electronic equipment. Any small aperture within a shielded electrical conductor conduit would provide for access of the pulse to the electrical conductor.
In the past, in order to prevent this superimposing of signals onto an electrical conductor, it has been common to encase the electrical conductor within a conduit formed of layers of braided metallic wires. In the constructing of such conduits in the past, it has been common to use clamps and other similar types of mechanical fastening devices in order to secure the ends of these layers of braided wires to the electrical connector fitting (such as backshells). However, it has been found that over a period of time and during installation of these conduits, these mechanical connections become loosened, resulting in the forming of small openings within the conduit. Any small opening within any conduit will make such conduit ineffective against protection of electromagnetic pulse. A single unprotected conduit within a bomber or fighter aircraft, that is exposed even minorly to a nuclear explosion, will result in that aircraft becoming immediately inoperative.
One type of method of connection between parts is called magnetic pulse forming. Magnetic pulse forming machines were first introduced in 1962. Since that time, magnetic pulse forming machines have been utilized to assemble a variety of manufactured articles which would be difficult and costly to assemble by conventional methods.
Magnetic pulse forming is an assembly technique which utilizes a high intensity magnetic field to expand or contract metallic workpieces. Magnetic pulse forming is based on the interaction of a rapidly changing magnetic field and the currents induced in an electrically conductive workpiece. Magnetic pulse forming is capable of compressing or expanding metal members without direct physical contact and without lubricants or torque normally encountered in rolling and spinning operations.
The high flux densities necessary to perform such magnetic pulse forming can be produced by discharging a capacitor through a coil for a period of a few microseconds. Thus, tremendous flux densities are produced for a short period of time. It is the magnetic force which moves the metal. In the case of a ring or band and this magnetic pulse being applied exteriorly thereof, this ring or band will in essence shrink and enclose a smaller area. This closing technique can be utilized to achieve an extremely strong, secure connection between different parts of a manufactured product.